Biogeographical Patterns in Pyrenomycetous Fungi and Their Taxonomy
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ISSN (print) 0093-4666 © 2010. Mycotaxon, Ltd. ISSN (online) 2154-8889 MYCOTAXON doi: 10.5248/114.281 Volume 114, pp. 281–303 October–December 2010 Biogeographical patterns in pyrenomycetous fungi and their taxonomy. 1. The Grayan disjunction Larissa N. Vasilyeva1 & Steven L. Stephenson2 [email protected] 1Institute of Biology & Soil Science, Far East Branch of the Russian Academy of Sciences, Vladivostok 690022, Russia 2Department of Biological Sciences, University of Arkansas Fayetteville, AR 72701, USA Abstract — In this paper the biogeographical pattern known as the Grayan disjunction is discussed with respect to pyrenomycetous fungi. The importance of considering biogeographical data in taxonomy is emphasized. Apiognomonia duschekiae is described as a new species, Biscogniauxia alnophila is proposed as a new name for B. mediterranea var. microspora, and Nemania sphaeriostoma is proposed as a new combination. Key words — Ascomycota, biogeography, distribution Introduction The importance of pyrenomycetous fungi in ecosystems as decomposer organisms cannot be overestimated, but many issues relating to their taxonomy, ecological preferences, and geographical patterns remain unclear on a global scale. Many pyrenomycetous fungi are restricted to particular hosts, and this association suggests that each species follows the distribution of its substrates, at least within uniform climatic zones, such as the cold temperate, warm temperate, or tropical zones. Indeed, there are circumpolar, circum-boreal, and pan-tropical pyrenomycete species, which some might consider to represent the primary distribution patterns for these fungi. More limited and peculiar patterns have been not discussed or even suspected. As a result, although the Asian mycobiotas are not similar to the European mycobiota, mycologists often have applied European names to morphologically similar Asian fungi because they assume that fungi are widely distributed. 282 ... Vasilyeva & Stephenson This paper discusses one biogeographical pattern that is usually termed the Grayan (Petersen & Hughes 2007) or Graysian (Tulloss 2005) disjunction in mycological literature. A number of plants and animals restricted to eastern North America where remnants of the ancient Tertiary flora persist can also occur in similar fragments of that flora in eastern Asia. Such a distribution, known as the famous “Asa Gray disjunction,” has been reported for species of fungi, primarily macrofungi (Hongo & Yokoyama 1978, Zang 1986, Wu & Mueller 1997, Yang 2000, Mueller et al. 2001) or lichenized fungi (Culberson 1972, Dey 1976, Wei & Biazrov 1991). An examination of the biogeographical patterns of pyrenomycetous fungi, which have not been considered previously, reveals a number of examples of Grayan distribution. Materials and methods The specimens mentioned in this study were collected by the senior author over many years throughout eastern Russia and the eastern United States. The basic map was taken from the web site http://commons.wikimedia.org and modified with our data. Photographs of ascomata were obtained using a Nikon D40x digital camera. Non-vicariance pattern Among the pyrenomycetous fungi are two species groups that demonstrate a Grayan distribution—those that occur in eastern Asia and eastern North America and those that display a vicariance pattern. Examples of the first group are Fracchiaea callista (Berk. & M.A. Curtis) Sacc. (Fig. 1), “Diatrypella informis” Ellis & Everh. (Fig. 2), Graphostroma platystoma (Schwein.) Piroz. (Fig. 3), and possibly Nitschkia floridana Fitzp. (Vasilyeva et al. 2010). Graphostroma platystoma occurs on dead branches of many kinds of trees, suggesting a wide distribution, but the fungus displays an affinity for eastern Asia and eastern North America. Similarly Diatrype albopruinosa (Schwein.) Cooke is found only in these two widely separated areas (Fig. 4); it has a broad tree host range in eastern North America (Rappaz 1987) but occurs only on Padus avium Mill. in eastern Russia. This is not the only example of an apparent substrate preference displayed by pyrenomycetous or loculoascomycetous fungi in eastern Russia. As another example, Byssosphaeria rhodomphala (Berk.) Cooke, occurs in eastern Russia only on Maackia amurensis Rupr., Phellodendron amurense Rupr., and P. sachalinense (F. Schmidt) Sarg., whereas in North America this species is known mostly on Populus spp. and Robinia pseudoacacia L. (Barr 1990). Both Populus and Robinia are present in eastern Russia, yet they apparently never serve as hosts to Byssosphaeria rhodomphala. Maackia and Robinia are both members of the Fabaceae, unlike the more distantly related Phellodendron (Rutaceae) and Populus (Salicaceae). The preference of the same Pyrenomycetes: the Grayan disjunction ... 283 Fig. 1. Approximate biogeographical distribution of Fracchiaea callista. For North America, Nannfeldt (1975) cited the Alabama, Ontario, Pennsylvania, and South Carolina localities while the westernmost record thus far from Arkansas is supported by Vasilyeva’s collection in the Buffalo National River; Connecticut, Maryland and Virginia are omitted. Localities in eastern Russia and South Korea are also based on the first author’s own collections. Scale bar = 0.75 mm. species for different hosts in different regions remains inexplicable — unless they are not the same species. If further studies prove them to be different species, they would represent a vicariance pattern in the Grayan distribution, discussed below. A good example of Grayan disjunction is Hypoxylon sphaeriostomum, known earlier from the USA (Georgia, Ohio, and Pennsylvania; Miller 1961) 284 ... Vasilyeva & Stephenson Fig. 2. Approximate biogeographical distribution of “Diatrypella informis”. Only two localities are indicated for eastern Russia, although this species is rather common on dead branches of Carpinus cordata Blume and is also found throughout the Primorsky Territory, including the Sikhote-Ainsky Nature Reserve, Kedrovaya Pad Biosphere Reserve, Ussuriysky Nature Reserve, the Vladivostok vicinity, and near Anisimovka (District Shkotovo). The eastern North American locality is based on Ellis & Everhart’s North American Fungi No. 2530 (“Diatrypella informis E. & E. n. sp. (type), on dead Carpinus, London, Canada, Apr. 1890, J. Dearness”). Scale bar = 1 mm. and recorded later from eastern Russia (Fig. 5). This species, which Ju & Rogers (1996) excluded from Hypoxylon (considering it to belong to Euepixylon), is treated herein as Nemania sphaeriostoma. Some species that display an apparent Grayan distribution have been reduced to synonyms, although they are morphologically distinctive and have a restricted distribution. For instance, Ju et al. (1998) regarded Biscogniauxia pezizoides (Ellis & Everh.) Kuntze as synonymous with B. repanda (Fr.) Kuntze. Pyrenomycetes: the Grayan disjunction ... 285 Fig. 3. Approximate biogeographical distribution of Graphostroma platystoma. North American localities listed by Pirozynski (1974) include Ontario and Quebec in Canada and Alabama, Arkansas, Florida, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, and Vermont in the USA. The eastern Russian specimens were collected in the Primorsky and Khabarovsk territories, the Amur Region, and on Sakhalin and Kunashir islands. Scale bar = 0.7 mm. However these two names might just as easily represent different species that are restricted to different host plants (mostly Ulmus and Sorbus, respectively) and their occurrence on different continents has already been noted (Pouzar 1979). The later discovery ofB. pezizoides in eastern Asia (Vasilyeva 1998) fits its distribution in the Grayan disjunction (Fig. 6). Another example is Diaporthella platasca (Peck) Wehm. (Fig. 7), first described from the Adirondack Mountains in eastern United States (Peck 1873) and later been shown (Wehmeyer 1933) to have smaller stromata and larger ascospores (16–23 µm long) than the European species D. aristata (Fr.) Petr. (ascospores 13–16 µm long). However, the two species were later confused and referred to D. aristata (Barr 1978, Chlebicki 2002). When D. aristata and D. platasca were found in eastern 286 ... Vasilyeva & Stephenson Fig. 4. Approximate biogeographical distribution of Diatrype albopruinosa. Some USA localities (Connecticut, the Dakotas, New Jersey, Mississippi) are from Rappaz (1987), and those for Canada (Manitoba, Ontario, Quebec, Saskatchewan) are taken from MycoBank (www.mycobank.com). The distribution range of this species in North America extends more to the west than for many other species with a Grayan disjunction. Only two collections are known from eastern Russia (in the Primorsky Territory and the Amur Region), but the senior author also found D. albopruinosa in China (Heilongjiang Province). Scale bar = 1 mm. Asia—on the Kamchatka Peninsula and Sakhalin Island, respectively—their differences became evident, not only with respect to morphology but also in their ecological preferences. Diaporthella aristata parasitizes living branches of birch trees (Betula ermanii Cham.), whereas D. platasca occurs on dead branches of low shrubs (Betula middendorffii Trautv. & C.A. Mey.). While describing the genus Diaporthella, Petrak (1924) noted the parasitic nature of D. aristata. However, the particular kind of substrate (trees or shrubs, in this case) might be of no importance, since Chlebicki (2002) indicated that D. aristata (with typical ascospores 14–16 µm long) occurs on living and dead twigs of a very low shrub (Betula nana